Have I been sold the wrong crankset?

[PJ520]

Time is running out before our tour so I had the LBS replace my 105 crankset. I thought the bearing cartridge was wearing out, the cranks had a bit of wobble in them. The man told me I'd have to go with external bearings and a Hollowtech crankset as they don't make the old stuff any more. Fair enough I says, go ahead and pay him to do the work. Now when i get my bike back there's a problem with the shifting that only turns up on the road; when I'm on the small ring shifting to the 28T on the rear sometimes the chain jumps, not just one cog but all the way to the smallest cog. The chain-rings look thin to me so I do a bit of internet poking and find that the FC-5703 the LBS installed is for 10 speed systems and my 520 is 9 speed, apparently the FC-3403 is the correct crankset for 9 speeds. My theory is that the thinner 10 speed ring has in effect moved the chain to the right a smidgin and that's causing my problem. Shifting with the two larger rings seems just fine. Can I fix my challenge by reusing the barely worn 24T ring from my old chain set or do I have to go through the misery of telling my LBS guy he's put the wrong set on?

I'm very uncomfortable with all this as I've known the man for years and he's always played right by me. On the phone he claims it's a matter of him 'working his magic' but I don't want to go on tour with something that needs magic that may leave me unable to climb hills or worse. He also said that the old 24T ring was thinner than the new one.

[Brucey]

so you are saying that when you are on the small chainring, you go to shift into the largest rear sprocket, and the rear mech slips down into a higher gear/smaller sprocket?

If so, there is a fault with the shifter most likely.

However if the chain is skipping/jumping under load, this is exactly what would happen if a new chain is fitted to a worn cassette. This is most likely to happen when the small chainring is used, because the chain tension is highest then.

If I understand you correctly, I don't think the chainset has anything to do with it...?

cheers

[PJ520]

I sincerely hope you're right about the derailer adjustment Brucey. Both the chain and cassette have less than 200 miles on them.

[Brucey]

although it is incredibly rare, its worth just acknowledging the possibility that your new chain is slightly out of spec. A few times I've heard of new chains in which the pitch is fractionally less than 1/2"; these can skip on new cogs in much the same way as a new chain can on slightly worn sprockets. Similarly there could be a stiff link perhaps?

cheers

[PJ520]

Now you come to mention the shifter. My LBS man did say that the detents on the Shimano bar-end shifter were worn (surprise only 51K on them) and I may be better off switching to friction mode. Frankly I didn't believe him but it sounds like he may have been right, I think I'll give it a try. Apparently new shifters are expensive and hard to come by. Thanks very much for giving it some thought Brucey.

[JohnW]

Now you come to mention the shifter. My LBS man did say that the detents on the Shimano bar-end shifter were worn (surprise only 51K on them) and I may be better off switching to friction mode. Frankly I didn't believe him but it sounds like he may have been right, I think I'll give it a try. Apparently new shifters are expensive and hard to come by. Thanks very much for giving it some thought Brucey.

I'd say that changing to friction levers/shifter will solve the problem - everything will be compatible with everything else and subsequent costs not as high........and the chain goes where YOU tell it to, not where a spring and ratchet decide. I use down-tube friction levers and have done since the year dot - no problem. You'll soon get used to it.

BUT - what I don't understand is why you needed to change the whole crankset because the bearing cartridge needed replacing - why couldn't you get a square-taper-end replacement? I bought a Stronglight BB cartridge from Spa (for a Shimano crankset) quite recently, and they're still on the Spa website.

Spa also sell some very good downtube levers - and I mean very good - I know, I'm using them.

Let us all know how things work out, won't you?

[PJ520]

Quite possibly you are right John. The reason I replaced the whole crankset was because I'd been reading about broken cranks on this forum and it made me a bit paranoid. The old ones had a lot of miles on them and the left crank had had a pedal stuck that took a lot of Manchester spannering to get it out, I thought it safer to get new cranks. While we were at it I found out that outside arm of my front derailer was worn and needed replacing. It seems that if it had gone much longer it was all set to grab the chain with all that that implies. I was always having to trim it but didn't trim enough it seems and the chain ended up wearing into it. I like to do my own maintenance but the wear on the derailer was something I would never have thought about, so much for moans about LBS's. Hope you can see what I'm talking about.

[tim_f]

9 speed bar ends are not hard to obtain - [url] http://www.chainreactioncycles.com/shim ... lsrc=aw.ds
[/url] but there is a big difference between RRP and on line price.

Or http://www.ebay.co.uk/itm/3x9-SPEED-IND ... 3641.l6368

for for non Shimanio ones (which only have an index mode)

[JohnW]

Quite possibly you are right John. The reason I replaced the whole crankset was because I'd been reading about broken cranks on this forum and it made me a bit paranoid. The old ones had a lot of miles on them and the left crank had had a pedal stuck that took a lot of Manchester spannering to get it out, I thought it safer to get new cranks. While we were at it I found out that outside arm of my front derailer was worn and needed replacing. It seems that if it had gone much longer it was all set to grab the chain with all that that implies. I was always having to trim it but didn't trim enough it seems and the chain ended up wearing into it. I like to do my own maintenance but the wear on the derailer was something I would never have thought about, so much for moans about LBS's. Hope you can see what I'm talking about.

First thing Pete - I'd not looked at your post as closely as I should have - you're on the West Coast of the USA and I'm in Halifax, England, which is about 7,000 miles from you..................rather different from a 25 mile ride (for me) to Harrogate and the wonderful Spa Cycles. Spa would have helped and advised you. You can park a bike outside their building, but there's nowhere for a 747.

From your photograph, your front changer doesn't look very worn to me, but that's just from a photo and my judgement is not necessarily to be trusted. Also, talk of downtube gear levers (shifters) is possibly irrelevant because your frame may not be able to accept them - i.e. no brazings and down-tube shape and size not able to accept band-on levers.

I know where I'd go in the UK to buy what you need, but that's no help to you.................and neither am I in fact.



If I'd been faced with the initial problem you describe I'd have simply bought a new taper-end BB bearing cartridge.

Note what Brucey says about the chain not always engaging on all sprockets - I always replace chains and sprockets together because they wear-in together and it's very common for old chains and new sprockets (and vice-versa) to not get on together - indeed I find it's normal.

Are you absolutely sure that the new chaninset is aligned with the sprockets EXACTLY as the old one was? Are you sure that the distances between chainrings are EXACTLY the same as on the old one? When I've made renewals like this I've often needed some small adjustment somewhere - and a fraction of a millimetre can make the difference that you're experiencing.

If you can put your bar-end shifter into non-index mode, why not try it and see how you get on with it? - you may need to make a very slight adjustment to the grub screw that controls the travel of the cage (in fact, that may be your problem and it would have been the first place that I'd have looked after a change of chainset).

Brucey is something of an oracle and well worth taking note of, and if 'colin531' responds, he may have come across this problem. From my own experience, and the reported experiences of all those with whom I ride, and from reports on this forum, my conclusion is that problems increase with sophistication. I never even changed to indexed gear changing, never mind the STI-type changing system. I'm not saying that the sophisticated systems don't work when in good and little-worn condition and properly adjusted because they do work, but the less sophisticated friction gear-change levers do also, and have done for 50 years to my limited knowledge.

What you could do is say to the LBS man something like : "it worked perfectly before you made the changes that you recommended, and now it doesn't - would you put it right please?"............but think carefully before he persuades you to spend big money on new equipment. That's what the manufacturers are wanting you to do when they replace in their range the simple parts that work, with sophisticated and expensive parts.

[PJ520]

Finally got it sorted. The shifter detents were worn out, I changed it to friction mode and everything is tickety boo. I feel confident going on tour now. Thanks John and Brucey for giving it some thought.

[JohnW]

Finally got it sorted. The shifter detents were worn out, I changed it to friction mode and everything is tickety boo. I feel confident going on tour now. Thanks John and Brucey for giving it some thought.

Ride on Pete - may it never rain on your ride. I'm happy for you.

[Brucey]

glad you have it sorted now!

FWIW if you are worried about crank breakage, the best thing to do is to inspect the cranks from time to time. If the cranks are silver (polished or anodised, not painted) then any cracks are quite obvious on the surface well before they break. Every failed crank that I've had a chance to inspect has shown the same thing, which is that the crack had progressed rather slowly until it was approximately half way through, and then the crank can break.

During an inspection, you would expect to see any cracks that are (say) about a tenth of the way through, so if they 'pass' then you can safely 'life' the cranks for another few thousand miles.

Cranks usually break in one of a few spots, and this varies with the model of crank and how it has been installed.

1) near the pedal eye
2) near the webs between the crank arm and the spider
3) at the square taper (not one-piece RH cranks)
4) part way along the crank (where there is damage or some other stress concentrator)

Needless to say, spraying everything with salty water (winter riding on treated roads) is about as bad a thing as you can imagine for most cranks but some (e.g. older TA and stronglight models) are very badly affected indeed.

cheers

[PJ520]

FWIW Per item 4. My LBS man told me that for a time Dura Ace cranks had a laser etching of the brand name on them and they used to break right at this etching.

[JohnW]

..........................
Cranks usually break in one of a few spots, and this varies with the model of crank and how it has been installed.

1) near the pedal eye
2) near the webs between the crank arm and the spider
3) at the square taper (not one-piece RH cranks)
4) part way along the crank (where there is damage or some other stress concentrator).......................

My experiences :

1). Never happened to me, but I've seen it. - cheap cranks and cheap pedals.
2). Never happened to me, but I've seen it - once - on a Dura-Ace of all things.
3). Never happened to me, and never seen it.
4). Oh heck yes - Stronglight 49D - right in the middle, right next to the depressed (stamped I think) "Stronglight etc............" logo - I've broken three that way - I'll never have 49Ds again (but not sure whether they're still made). One went with such a bang and I made sudden and painful contact with the top tube. If anything is etched, or forged , or stamped into an alu crank - don't buy it!!!!!